Method of coloring textiles with pigments



Patented Feb. 29,1944

METHOD OF COLORING TEXTILES WITH ",IIGMENTS Norman S. Cassel, Ridgewood,N. J., assignor to Interchemical Corporation, New York, N. Y., a

corporation of Ohio No Drawing. Application August 3, 1940, Serial No.351,204

2 Claims.

This invention relates to the dyeing of textile fabrics, and hasparticular reference to a new and novel method of dyeing fabrics withpigment, characterized by the metered application of carefullycontrolled amounts of pigmented lacquer emulsions to the fabric.

Textile fabrics are almost universally colored by being treated with asolution of a dyestufi in an aqueous medium; the soluble dyestuff isprecipitated in the capillaries of the fibers of the yarns, or is causedto adhere chemically to the textile material. In some cases,water-insoluble dyestuffs having an affinity for certain syntheticfabrics are used in solution in other solvents. Since all of thesedyestuffs must be capable of conversion from the soluble state to theinsoluble state in contact with the fiber, and since they must beresistant to a great variety of deteriorating influences, the problem ofinexpensive, fast textile colors has always been a pressing one.

The ready availability and low cost of the insoluble pigment colors hasprompted many investigators to study the application of these colors forthe dyeing of textiles, but with relatively little success. Except wherethe pigment is incorporated into a spinning solution used for makingsynthetic fibers, unaided mechanical adhesion of the pigment to theyarns has proven unsuccessful. Attempts to cause the pigment to adhereto the fabric by the use of binders hav likewise proven abortive, for avariety of reasons. A principal cause has been the failure of thepigment binders to withstand the severe conditions to which textiles aresubjected; the failure of the binder leaves the pigment in meremechanical contact with the fabric, whence it is easily removed. Asecond important difficulty has been that of even application of verysmall quantities of pigment plus binder, so that the fabric is coloreduniformly. The problem is presented by the tendency of pigments toflocculate or settle out in highly'disperse media, so that uniformapplication is very difficult.

It has been proposed to dye textile fabrics with pigmented lacquersemulsified as the discontinuous phase of a lacquer-in-water emulsion,using heat-convertible synthetic resins as binder in the lacquer. Suchemulsions give satisfactory uniform dyeings on fabrics, when the fabricsare immersed in the bath and the excess color squeezed off. However, thecloth must be heated after the dyeing operation, both to evaporate thewater and solvent, and to set th resin. If the fabric is not maintainedin a uniform state of tension, or if e d y i d e unevenly, the colorwill tend to migrate and give a streaked appearance. This tendency isconsiderably aggravated as cloth thickness increases, so that shirtingbroadcloths and heavier fabrics must be handled with special equipmentand with such extreme care that rapid drying is impossible. As a result,the emulsion pad dyeing has for the most part been restricted to ratherthin fabrics, or to special cases with heavier fabrics.

I have discovered that cloth may be dyed with emulsions of pigmentedlacquers in water, while substantially eliminating the tendency of thelacquer to migrate, by applying a very thin emulsion to the cloth insufiicient quantity to thoroughly permeate the cloth, while limiting theamount of material to about one-half of What the cloth will absorb froma bath and retain after being wrung out under substantial pressure.Since most cotton and rayon cloths retain about equal weights of liquidunder such treatment, this limit may be more simply stated as a fractionof cloth weight.

The dye liquid may be applied to the cloth by forming a thin film on aroll coating machine, and then transferring it to the cloth; but Iprefer to use a uniformly knurled cylinder wiped with a doctor blade,since the amount of liquid applied can be most easily controlled by thismethod, and the application is far more uniform than with a roll coater.

I believe that migration is avoided by this process because of the factthat no liquid water is present on the fabric during the dryingoperation, the fabric having absorbed the water.

Typical examples of my invention are the following:

' EXAMPLE 1 Clear emulsion Parts by weight Solvent solubleurea-formaldehyde resin solution (50 resin, 30 butanol, 20 xylene) 5.0Alkyd resin solution (50 resin, 50 pine oil) 15.0 Pine oil 2.5 Solvesso#2 (hydrogenated petroleum naphthat-boiling range l35177 C.) 27.5 areemulsified by adding slowly, with stir- Sodium lauryl sulfate 2.5 Water47.5

to produce a stable emulsion containing 10% resin solids. The alkydresin is a 33% soya oil modified glycerol phthalate, acid number about5.0.

EXAMPLE 2 Yellow emulsion Parts by weight A 20% aqueous pulp of yellowpigment, prepared by diazotizing dichlorbenzidine and coupling withacetoacetanilide- 6.5 A 35% aqueous solution of sulfonated tannin .25are stirred together on a high speed mixer, and added to a mixture of'Alkyd resin solution of Example 1 8.5 Pine nil 10.0 I

The resultant water-in-lacquer emulsion is diluted with- Parts by weightSolvesso 48.0

and added slowly, on a high speed mixer, to

a solution of- Sodium lauryl sulfate 2.0 Water 24.75

The emulsion inverts as it enters the water, producing a stablelacquer-in-water emulsion having 1.3% pigment solids, and 5.5% resinsolids. This is preferably mixed with four parts of water and one partof the clear emulsion of Example 1, before using. The resultant dyeingsolution then carries a maximum of .21% pigment and 2.6% resin solids.

When used in normal fashion, this emulsion migrates badly on drying.When applied by an intaglio plate or roll coating method, so that from40 to 50% of the cloth weight is absorbed, uniform non-migrating dyeingsare obtained.

EXAMPLE 3 .4220 blue Parts by weight 20% aqueous pulp of blue pigmentformed by diazotizin dianisidine, and coupling it with the sodium saltof the ortho toluidide of beta oxy naphthoic acid (Naphthol Thislacquer-in-water emulsion contains 1.1

pigment solids and 4.1 resin solids. On minimum dilution with 4 parts ofwater and 1 part of clear, the pigment solids of the dyebath is 1.8, andthe resin solids 2.3%. Like Example 2, it produces a migrating color byordinary means, but a satisfactory job when applied by gravure methods.

While I have disclosed but a few examples of dyeing emulsions, theexample can be multiplied indefinitely without departing from the scopeof my invention. Where resistance to washing and dry cleaning are notimportant, substantially any pigments or binders may be used, providedcare is taken to maintain th conditions necessary for appearance andhand. Where qualit dyeing is desired, however, the pigments and bindersmust be so chosen as to resist dry cleaning solvents and washing. Asindicated above, best results are obtained with the carbamideformaldehyde resins, including the resins made from formaldehyde andurea, thiourea, melamine, and other urea derivatives and substitutedureas. Phenol formaldehyde resins, and other resins which can be setrapidly at elevated temperatures, may also be used, although the resultsobtained with them are not as satisfactory as those obtained with thecarbamide formaldehyde resins,

Any emulsifying agent can be used to prepare the emulsions, provided itmakes a stable emulsion with the particular lacquer. I have successfullyused Lamepon A (protein composition products condensed with fattyacids), Santomerse D (sodium salts of alkyl substituted arylsulfonates), various sodium alkyl sulfates, and others, as well as thoseshown in the examples.

The term lacquer, as used in the claims, refers to solutions, involatile organic solvents, of filmforming binders or thickeners whichare waterinsoluble, and which are plastic or solid, so that when thesolvent evaporates, the binder forms a film which is substantially setwhere deposited.

I claim:

1. The method of pigment dyeing textile while avoiding migration ofcolor on drying, which comprises applying to a textile fabric a thin pigmented lacquer-in-water emulsion whose wet weight is not in excess of offabric weight, evenly distributing the emulsion through the fabric bypressure, and drying the fabric.

2. The method of pigment dyeing textiles while avoiding migration ofcolor on drying, which comprises simultaneously applying to a textilefabric a thin pigmented lacquer-in-water emulsion whose wet weight isnot in excess of 50% Of fabrlc weight and evenly distributing theemulsion through the fabric by pressure, and thereafter drying thefabric.

NORMAN S. CASSEL.

